• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.46-52
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• 2003

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.

• The Journal of Korea Robotics Society
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• v.3 no.2
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• pp.106-111
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• 2008

This paper presents a decentralized coordination for a small-scale mobile robot teams performing a task through cooperation. Robot teams are required to generate and maintain various geometric patterns adapting to an environment and/or a task in many cooperative applications. In particular, all robots must continue to strive toward achieving the team's mission even if some members fail to perform their role. Toward this end, given the number of robots in a team, an effective coordination is investigated for decentralized formation control strategies. Specifically, all members are required first to reach agreement on their coordinate system and have an identifier (ID) for role assignment in a self-organizing way. Then, employing IDs on individual robots within a common coordinate system, a decentralized neighbor-referenced formation control is realized to generate, keep, and switch between different geometric shapes. This approach is verified using an in-house simulator and physical mobile robots. We detail and evaluate the formation control approach, whose common features include self-organization, robustness, and flexibility.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2008-2011
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• 1998

When the vector control, which does not need a speed signal from a mechanical speed sensor, it is possible to reduce the cost of the control equipment and to improve the control performance in many industrial application. This paper describes a rotor speed identification method of induction motor based on the theory of Model Reference Adaptive System(MRAS). The identifier execute the rotor speed identification so that the vector control of the induc-tion motor may be achieved. The improved auxiliary variable are introduce to perform accurate rotor speed identification. Simulation and experimental result show the validity of the proposed control method.

• Journal of Power System Engineering
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• v.4 no.4
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• pp.108-115
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• 2000

The continuous chip in turning operation deteriorates the precision of workpiece and can cause a hazardous condition to operator. Thus the chip form control becomes a very important task for reliable turning process. Using the difference of energy radiated from the chip, the chip form is identified using the neural network of supervised data. The feed mechanism is adjusted in order to break continuous chip according to the result of the chip form recognition and shows a good approach for precision turning operation.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.415-417
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• 2004

정보통신 및 인터넷의 급속한 발전으로 디지털 콘텐츠의 유통이 활발해지고 있으나 디지털, 콘텐츠에 대한 서비스 방식이 위치정보를 가지고 서비스하는 URL(Uniform Resource Locator)방식의 문제점과 기존의 물리적인 저작물r이 디지털 콘텐츠로 전환되면서 기존의 식별자로는 디지털 콘텐츠의 특성을 충족시키는 식별이 미흡하고 한계가 있다. 따라서, 해외 주요 디지털 콘텐츠 서비스기관의 식별체계 활용사례를 분석하고 그 결과를 토대로 한국과학기술정보연구원(KISTI) 고유 식별자인 KOI(Kisti Object Identifier)를 개발하고 개발된 KOI를 기반으로 과학기술분야 전자원문 연계시스템을 설계 및 구현하였다.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.3
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• pp.295-300
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• 2008

In this paper, a new looper controller is proposed to minimize the tension variation of a strip in the hot strip finishing mill. The proposed control technology is based on a receding horizon control (RHC) to satisfy the constraints on the control input/state variables. The finite terminal weighting matrix is used instead of the terminal equality constraint. The closed loop stability of the RHC for the looper system is analyzed to guarantee the monotonicity of the optimal cost. Furthermore, the RHC is combined with a 4SID(Subspace-based State Space System Identification) model identifier to improve the robustness for the parameter variation and the disturbance of an actuator. As a result, it is shown through a computer simulation that the proposed control scheme satisfies the given constraints on the control inputs and states: roll speed, looper current, unit tension, and looper angle. The control scheme also diminishes the tension variation for the parameter variation and the disturbance as well.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.645-648
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• 1995

We propose speed controller of AC servo motors using adaptive two-degrees-of freedom controller design. The overall control system consists of three elements: a forward speed controller, parameter identifier and disturbance observer. This servosystem can improve the characteristics of the closed loop systems with the disturbance observer by eliminating the disturbance torque without changing the command input response. Moreover, the system can be adaptable to the parameter variation by employing adaptive scheme. We will show the control performances through the simulation results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.2
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• pp.127-136
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• 1989

This paper describes the parameter convergence properties of an adaptive system to identify a single-input single-output plant model. It is demonstrated that, by using power spectrum analysis, the persistency of excitation (PE) condition in order to guarantee the exponential stability of the adaptive control system can be transformed into the positive definite behavior for the auto-correlation function matrix of adaptive signal. The existence of parameter nominal values can be analyzed by this condition and the convergence rates of parameter are determined by examining the auto-correlation function. We may use the sufficient richness (SR) of input spectrum instead of the PE condition to analyze the parameter boundedness. It can be shown that the eigen values of the auto-correlation function are always related with adaptive gain, input amplitude and positions or numbers of input spectra. In each case, the variation of parameter convergence rate can be also verified.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1107-1109
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• 1996

In this paper, we discuss the automatic recognition system of vehicle types and licence plate numbers using artificial neural networks, which will be used as vehicle identifier. We confine to expose the vehicle licence number for violating bus lane and stolen cars. Therefore, the vehicle height, width and distribution profile are used as the feature parameters of vehicle type. This system is composed of two parts: one is an image preprocessor of vehicle images and the other one is a pattern classifier by neural networks. The experimental results show that our method has good results for the recognition of vehicle types and numbers.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2003.05a
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• pp.490-494
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• 2003

운송 컨테이너의 식별자를 추출하고 인식하는 것은 컨테이너 식별자들의 크기나 위치가 정형화되어 있지 않고 외부의 잡음으로 인하여 식별자의 형태가 훼손되어 있기 때문에 어렵다. 본 논문에서는 이러한 특성을 고려하여 컨테이너 영상에 대해 Canny 마스크를 이용하여 에지를 검출하고, Canny 마스크가 적용된 영상에서 수직·수평 히스토그램을 적용하여 컨테이너의 식별자 영역을 추출한다. 추출된 컨테이너의 식별자 영역을 삼각형 타입의 퍼지 이진화 방법을 적용하여 이진화하고 이진화된 컨테이너 식별자 영역을 윤곽선 추적 알고리즘으로 개별 식별자를 추출한다. 제안된 방법의 성능을 평가하기 위하여 실제 컨테이너 영상에 적용한 결과, 기존의 방법보다 컨테이너의 식별자 추출에서 우수한 성능이 있음을 확인하였다.